What this PDF compressor can and cannot do
Online PDF compressors with dramatic results usually re-encode every image in the document on a powerful server. This tool works entirely in your browser so your file is never uploaded, and it is honest about what that allows. It offers two approaches, and it always tells you how much smaller the result is, so you can decide whether it is worth keeping.
Lossless clean-up
The first mode opens the PDF with pdf-lib and saves it again using compact object streams. Documents produced by some scanners, older software or repeated editing often contain redundant structure that this removes. Text stays selectable, links keep working and images are untouched, so there is no visible change. The saving varies a lot: sometimes ten to thirty percent, sometimes almost nothing for files that were already well optimised. If the result would be larger than the original, the tool says so rather than handing you a bigger file.
Balanced and strong modes
The other two modes draw each page with PDF.js, the PDF engine used in Firefox, and store it as a JPEG image at 120 or 96 dots per inch. This can shrink scanned documents and photo-heavy PDFs dramatically, because scans are often stored at 300 dpi or more. The trade-off is important: the pages become pictures, so the text can no longer be selected, searched or copied, links stop working and fine print may look softer. That is usually fine for a scanned form you need to email, and not fine for a contract you will need to search later. Keep the original file.
Choosing a mode
- A digital document from Word or a website: start with lossless. Big savings usually need the file to be re-exported from the original application with image compression enabled.
- A scan or a PDF of photos: try balanced first. Use strong only if the file still exceeds an email or upload limit.
- Very short documents: the fonts embedded in the file may be most of its size, and no mode can remove them safely.
Privacy
Every step runs on your device, using libraries served by this site. No copy of the document is sent or stored anywhere.